1. Field of the Invention
This invention relates to Venetian blinds and, more particularly, to the construction of louvers or slats for use in such blinds.
2. Description of the Prior Art
Wooden-slat Venetian blinds, once popular forty or fifty years ago, are coming back into vogue for certain custom installations, for use in homes in medium and upper price range, and in certain offices and institutions after having been substantially displaced by metal-slat Venetian blinds. The wooden-slat Venetian blinds tend to provide a richer look, more in keeping with current decorator trends.
Wooden-slat Venetian blinds, as presently constructed, comprise a plurality of slats or louvers supported, at least toward the opposite ends of the slats (opposite sides of the blind), by so-called ladders comprising a pair of angle or tilt control strings located on opposite sides of the slats and a lift string extending vertically through the centers of the slats. Extending generally horizontally between the tilt strings and spaced vertically in accordance with the width of the slats, is a series of cross strings or tapes which serve to support the respective slats in appropriately spaced relationship. Each slat is, of course, provided with a central opening through which the lift string extends. This opening is elongated in the transverse direction of the slat in order to permit the slats to be tilted through a substantial angle in opening or closing the blind without interference between the slats and the lift strings. By varying the vertical positions of the tilt strings of a single ladder with respect to each other--and thereby the angles of the cross tapes extending between them--the slats are rotated in unison, thereby opening and closing the blind. The blind may be lifted entirely to the top of the associated window or other space where it is installed by causing the lift string to be pulled upwardly, as over a pulley arrangement in the head piece of the blind, thereby lifting the bottom rail of the blind and pulling all of the slats up with it as the slack is taken up by the lift string.
It may readily be seen that the wooden slats of blinds which are so constructed have an inherent weakness in the longitudinal portion adjacent the transverse openings for the lift strings. When a slat breaks, it is most likely to fail at this point. Also, wooden slats have somewhat of a tendency to warp, thus presenting a problem which is not present in the Venetian blinds made of metal slats or some other material. While it is a relatively simple matter to remove an individual slat from the blind simply by breaking it at the point where the ladders are situated, a new slat cannot be installed without taking apart the entire blind.
Sectioned louvers for Venetian blinds have been known in the prior art; see the Carreras et al. U.S. Pat. No. 2,170,938, for example, which discloses a Venetian blind louver fabricated of sections which are joined by especially constructed metal clips. The stated purpose of this construction is to adapt the louvers to extra large windows or windows of odd dimensions from louvers initially manufactured to lengths of certain standard dimensions.
There are numerous examples in the prior art of means for detaching slats from blinds without disassembling the entire blind. Among these are slats provided with T-shaped end slots as in the Carreras et al. patent and in U.S. Pat. Nos. 2,521,151 of Cusick and 2,643,713 of Mayer; side slots are disclosed in U.S. Pat. Nos. 2,123,010 of Kahn, 2,588,550 of Martin et al. and 3,086,586 of Wolfe; detachable cords as in the U.S. Pat. Nos. 2,012,034 of Brent, 2,547,260 of Foglio, and 2,314,461 of Schaefer; and detachable clips as disclosed in U.S. Pat. Nos. 2,796,927 of Evans, 2,532,617 of Hauser et al., 2,365,004 of Rice et al., 2,122,224 and 2,152,117 of Wade et al., 2,311,716 and 2,576,160 of Walker, and 2,317,659 of Williams. None of these, insofar as can be determined, deals with the problem which is solved by the present invention.